Lol, for some reason watching other people fail puts me in a better mood. You have to admit, when you see that stuff happening to another person you have the thought "I'm glad I'm no them" going through your head.
The thing that always gets me in these videos is the people who don't even put their arms out to break their fall as they face plant into the ground. I did the bmx freestyle thing when I was younger and I can tell you that crashing is a skill. I've known multiple novice riders who were injured jumping the smallest stuff (including myself) but after you get good at it a failed 360 over a box jump results in a few scrapes at most usually.